This specification relates to serving expandable content items for presentation in content item environments.
Sponsored content (e.g. advertisements, deals or special offers) can be provided over the Internet to various user devices. For example, a web page can include slots in which sponsored content can be presented. These slots can be defined in the web page or defined for presentation with a web page, for example, along with search results or other content. Sponsored content can also be delivered through dedicated web portals or applications executing on the user devices.
Some content items are expandable. For example, a content item can be initially presented in an unexpanded form as a 728×90 pixel graphical item. When an expansion event occurs, an expanded view of 728×270 pixels can be presented. The expanded view of the content item should fit inside the web page as rendered on the browser to present unwanted effects such as clipping.
Expandable content items may expand uni-directionally or multi-directionally. A uni-directional expandable content item can only expand in one direction, such as “down”, “up”, “left”, or “right.” A multi-directional expandable content item, on the other hand, can expand in two or more directions.
Because the content items are served for particular content item environments in a web page, a client device typically requests the content items when the page is being rendered at the client device. The content item management system that receives the request attempts to select, in response to the request, content items that can expand in a direction for which there is available space for expansion on the web page. For example, a content item environment at the top of a web page should not receive an expandable content item that expands only in the “up” direction; rather, it should receive an expandable content item that expands in the “down” direction (or, alternative, in one or more of the “down”, “right” and “left” directions, if there is space available for expansion in the “right” and “left” directions as well).
Content item serving systems use various models to determine the expansion directions available for a request. The models may be resource specific or site specific, or a combination of both. Resource specific models are based on observed expansions of an expandable content item environment for a particular resource, and site specific models are based on the observed expansions of an expandable content item environment for multiple resources of the site. While these models tend to provide adequate prediction coverage, there are requests for which the data that are available for predicting an expansion direction are insufficient. Consequently it may not be possible to determine the expansion direction of the particular content item environment.